Process for dehydrogenating hydrocarbons



Patented Sept. 24, 1946 I I I 2,408,131

T iN' T- omcE 1 l xi Yce h es in, Baton Badge, La; assi leatie "StandardOilDey lopment C any, a

ati ethdewa e No Drawing. Application October 2 '1 1951,

- "Seria 3 Q (Cl. 260-6833) 1 ..,i I t, 2 I I I have now found that a catalyst comprising a major proportion of aluminum oxide and a minorproportion of chromium oxide can bemade I, I I I I substantially more heat'ijes'istantand fby 'YJt'oi a s 'ubstant'ialfe entj'wlien heated 5 reta i i its"ac tivity at s'ub sta tially higher tein totmperatures at" which 'the' knowntypes o'f peratures if approximately o I) I I V cata ysts 1051,: their act v ty; dwjith' e m o miu aide i erated iq e x de rea mh see c i re i ta ed. ttat'a ezea i ar s n aha it. 6%. alt mete .Q "9 i miu aexide a d air Pitt. tateni e ata fesbetweee i tqaed l F with: ut. ses its a ti itv t a t a p eciable exitent Wh 7 cata s came fi e 2% el m nate iide and 6 geran m 9X 6 se a t tti??- tial amount of it aetiu. r .sieeheetss'l at 1 00 F. a

invenvert the nitrate to the oxide. In order to increase the mechanical Str'eng'thand durability of the catalyst it may be heated to a high temperature, equal amounts. say above 1000 F., at which temperature a sub- These catalysts may be prepared by impregstantial amount of volatile matter and moisture hating Activated Alum a, a mina gels, peptized is driven off. In general it may be said that the a umina g b alumina lrlydraiiesv and higher the temperature to which this type of other forms of aluminum oxide with a mixture atalyst i heated, themore rugged it will become, of solutions of chromium and nickel nitrates and However, it is noted that as the temperature of then heating the resulting mass to temperatures heating is increased, the catalyst tends to become ween 6 0 and 800 F. The concentration of less active. chromium and nickel nitrates in the solution are The ability of a catalyst to retain its activity ju so that the fin l he t d m s will conwhen heated to high temperatures is important tain the desired quantities of Chromium and not only in the preliminary t treatment to nickel oxides. It Will be understood that soluble increase mechanical strength but also in the catsalts Chromium and nickel other than the alytic dehydrogenation reaction itself and in the n s y b u f r impr n in h l regeneration of the catalyst when its activity has mimlm 0Xidebeen reduced by the deposition of carbonaceou The following experimental data indicate the contaminants thereupon. Thus it frequently heat resistant p p s 0f the improved happens during the dehydrogenation reaction, l/St n pa s n With t o f t e OWn and particularly during the regeneration, that Catalyst! excessively high temperatures may be developed WO at ysts a e p p e One st g of in local spots in the catalyst mass and if these Activated Alumina d Chromium Oxide temperatures are high enough to cause loss of and the other consisting of 6% ct vated activity it can be seen that care must be taken Alumina, 2% chromium oxide and 2% nickel to prevent such local overheating. In regenoxide. Isobutane is passed over each catalyst at crating the catalyst it is of great advantage to a rate of 175 volumes of isobutane per volume of be able to conduct the regeneration at as high at yst l hour at a temperature f 1075 a temperature as possible because this means In the first experim t t e C a y s are not D that the necessity for constant cooling. of-the t d to a h t p In the e o d, catalyst mass is greatly reduced, It can b Seen third and fourth experiments the catalysts are therefore that if the catalyst is one which loses heated to temperatures of 1600 F., 1800 F. and its activity when heated to certain temperatures, 2000 F. respectively. The following tables show care must be taken to prevent these temperatures the results obtained. In the table the catalyst from being reached either during thereaction containing 4% chromium oxide and no nickel period or during the regeneration period. Oxide will be desig ted as Catalyst A, and the catalyst containing 2% chromium oxide and 2% nickel oxide will be designated as catalyst B:

It will be noted that when the two catalysts are heated to temperatures of 1600 F., they are substantially equivalent in activity as represented by the fact that about the same amount of unsaturates are produced and about the same percentage of the unsaturates consists of isobutylene. However, when the catalysts are heated to 1800 F., it will be noted that there is a marked decrease in the percent of unsaturates and percent of isobutylene produced with catalyst A, whereas the decrease with catalyst 13 is not nearly so great. This tendency is even more marked when both catalysts are heated to 2000 F.

I'claim:

l 1. The process of dehydrogenating hydrocarbons having from 2 to 5 carbon atoms which alyst which consists of about 96% by weight of aluminum oxide, 2% by Weight of chromium oxide and 2% by weight of nickel oxide, and which has been heated to a temperature between 1800 and 2000 F.

2. The process of dehydrogenatinghydrocarbons having from 2 to 5 carbon atoms which comprises passing the hydrocarbons at dehydrogenating temperatures and pressures over a catalyst which contains about 96% by Weight of aluminum oxide, 2% by weight of chromium oxide and 2% by weight of nickel oxide, and which has been heated to a temperature between 1800 and 2000 F., and regenerating the catalyst by removing coke deposits at intervals substantially at temperatures of the regeneration reaction without constant cooling.

3. The process of dehydrogenating hydrocarbons having from 2 to 5 carbon atoms which comprises passing the hydrocarbons at dehydrogenating temperatures and pressures over a catalyst which consists of a major proportion of aluminum oxide and minor substantially equal proportions of chromium oxide and nickel oxide and which has been heated to a temperature between 1800 and 2000 F.

4. The process of dehydrogenating hydrocarbons having from 2 to 5 carbon atoms which comprises passing the hydrocarbons at dehydrogenating temperatures and pressures over a catalyst which contains a major proportion of aluminum oxide and minor substantially equal proportions of chromium oxide and nickel oxide and which has been heated to a temperature comprises passing the hydrocarbons at dehydrogenating temperatures and pressures over a catbetween 1800 and 2000 F., and regenerating the catalyst by removing coke deposits at intervals substantially at temperatures of the regeneration reaction without constant cooling.

ALEXIS VOORHIES, JR. 

